1. Field of the Invention
The present invention relates generally to automotive braking systems, and in particular is concerned with a poppet assembly for a traction control modulator.
2. Description of the Related Art
A traction control system in an automotive braking system permits control of wheel spin at each driven wheel. A traction control system improves the ability to maintain vehicular stability and acceleration (drive-traction) under changing road and vehicle load conditions.
Oftentimes, a traction control system utilizes a type of engine modulation in combination with actuation of a braking system. The present invention is related to the aspect of traction control concerned with automated actuation of the vehicle brakes.
U.S. Pat. No. 5,207,488, assigned to the present assignee, discloses a traction control modulator having a piston attached to a non-rotative nut. The piston is retracted by a power screw threadably engaged with the nut. A poppet assembly or plunger is biased away from the piston by a spring. The plunger includes an elastomeric sealing head which contacts a metal housing to block fluid flow to a master cylinder during operation of the traction control system.
In the event that operation of the traction control system must be terminated, a pressure differential between the master cylinder and a caliper assembly can be created. This condition is known as "pressure lock". The pressure differential can be great enough to pull and tear a sealing head from a plunger, thereby adversely affecting the seal by the sealing head.